Steric hindrance can both positively and negatively influence catalysis. In some cases, it can be used to control the selectivity of a reaction, such as in asymmetric catalysis where large substituents are used to block certain pathways, thereby directing the reaction to produce the desired enantiomer. Conversely, steric hindrance can also reduce the rate of a reaction by preventing the substrate from properly interacting with the active site of the catalyst.
